The present technology relates to an exercise machine that utilizes a linear motor to provide resistance to a force generated by a user performing an exercise, and to linear motor systems for use in such exercise machines.
Typical physical fitness training equipment utilizes a weight stack sliding on vertical rods under the influence of gravity as the force producing element. Movement of the weight stack by the user is caused by tension created in a cable that attaches to the top of the weight stack. The weight stack, and more specifically gravity acting on the weight stack, is the force producing element that provides resistance to a pulling force generated by the user during an exercise routine. The weight stack is movable vertically through a series of pulleys and levers utilizing hand grips, bars, or other types of user devices to perform an exercise by lifting the weight stack. For example, FIG. 1 illustrates a known example of an exercise machine 100, with which a user can perform a number of exercises using a weight stack 114. The weight stack 114 slides along two parallel vertical rods 106 and 108 when the user of the exercise machine 100 pulls on the cable 120 during the course of performing an exercise routine. The vertical rods 106 and 108 are secured to the exercise machine 100 by a bottom weight support rod bracket 116 and a top weight support rod bracket 104. An attachment bolt 102 is used to secure the top weight support rod bracket 104 to the frame of the exercise machine 100. The cable 120 is connected at one end to a cable attachment bolt 110 which serves to secure the cable 120 to a weight support assembly 118 which is part of the weight stack 114. A weight selection pin 112 may be inserted into one of a plurality of holes in the weight stack 114, in order to select the amount of weight in the stack which will be moved during the performance of the exercise routine by the user. The other end of the cable 120, after passing through various pulleys, may be connected to various attachments (not shown) for use in performing the selected exercise, all in a known manner.
Other non-electronic weight lifting systems have also been utilized by designers of weight lifting equipment that offer variable resistance or fixed weight. In one example, large rubber bands have been utilized to produce resistance. In another example, hydraulic and/or pneumatic cylinders have been designed into weight lifting machines to produce resistance. Multiple weight stacks have also been incorporated into weight lifting equipment whereby additional weight can be added in a routine as the routine progressed by having the first weight stack come in contact with a secondary weight stack as the exercise progresses, adding predetermined weight during the routine.